kernel/irq/manage.c

   1 /*
   2  * linux/kernel/irq/manage.c
   3  *
   4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   5  * Copyright (C) 2005-2006 Thomas Gleixner
   6  *
   7  * This file contains driver APIs to the irq subsystem.
   8  */
   9
  10 #include <linux/config.h>
  11 #include <linux/irq.h>
  12 #include <linux/module.h>
  13 #include <linux/random.h>
  14 #include <linux/interrupt.h>
  15
  16 #include "internals.h"
  17
  18 #ifdef CONFIG_SMP
  19
  20 /**
  21  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  22  *      @irq: interrupt number to wait for
  23  *
  24  *      This function waits for any pending IRQ handlers for this interrupt
  25  *      to complete before returning. If you use this function while
  26  *      holding a resource the IRQ handler may need you will deadlock.
  27  *
  28  *      This function may be called - with care - from IRQ context.
  29  */
  30 void synchronize_irq(unsigned int irq)
  31 {
  32         struct irq_desc *desc = irq_desc + irq;
  33
  34         if (irq >= NR_IRQS)
  35                 return;
  36
  37         while (desc->status & IRQ_INPROGRESS)
  38                 cpu_relax();
  39 }
  40 EXPORT_SYMBOL(synchronize_irq);
  41
  42 #endif
  43
  44 /**
  45  *      disable_irq_nosync - disable an irq without waiting
  46  *      @irq: Interrupt to disable
  47  *
  48  *      Disable the selected interrupt line.  Disables and Enables are
  49  *      nested.
  50  *      Unlike disable_irq(), this function does not ensure existing
  51  *      instances of the IRQ handler have completed before returning.
  52  *
  53  *      This function may be called from IRQ context.
  54  */
  55 void disable_irq_nosync(unsigned int irq)
  56 {
  57         struct irq_desc *desc = irq_desc + irq;
  58         unsigned long flags;
  59
  60         if (irq >= NR_IRQS)
  61                 return;
  62
  63         spin_lock_irqsave(&desc->lock, flags);
  64         if (!desc->depth++) {
  65                 desc->status |= IRQ_DISABLED;
  66                 desc->chip->disable(irq);
  67         }
  68         spin_unlock_irqrestore(&desc->lock, flags);
  69 }
  70 EXPORT_SYMBOL(disable_irq_nosync);
  71
  72 /**
  73  *      disable_irq - disable an irq and wait for completion
  74  *      @irq: Interrupt to disable
  75  *
  76  *      Disable the selected interrupt line.  Enables and Disables are
  77  *      nested.
  78  *      This function waits for any pending IRQ handlers for this interrupt
  79  *      to complete before returning. If you use this function while
  80  *      holding a resource the IRQ handler may need you will deadlock.
  81  *
  82  *      This function may be called - with care - from IRQ context.
  83  */
  84 void disable_irq(unsigned int irq)
  85 {
  86         struct irq_desc *desc = irq_desc + irq;
  87
  88         if (irq >= NR_IRQS)
  89                 return;
  90
  91         disable_irq_nosync(irq);
  92         if (desc->action)
  93                 synchronize_irq(irq);
  94 }
  95 EXPORT_SYMBOL(disable_irq);
  96
  97 /**
  98  *      enable_irq - enable handling of an irq
  99  *      @irq: Interrupt to enable
 100  *
 101  *      Undoes the effect of one call to disable_irq().  If this
 102  *      matches the last disable, processing of interrupts on this
 103  *      IRQ line is re-enabled.
 104  *
 105  *      This function may be called from IRQ context.
 106  */
 107 void enable_irq(unsigned int irq)
 108 {
 109         struct irq_desc *desc = irq_desc + irq;
 110         unsigned long flags;
 111
 112         if (irq >= NR_IRQS)
 113                 return;
 114
 115         spin_lock_irqsave(&desc->lock, flags);
 116         switch (desc->depth) {
 117         case 0:
 118                 printk(KERN_WARNING "Unablanced enable_irq(%d)\n", irq);
 119                 WARN_ON(1);
 120                 break;
 121         case 1: {
 122                 unsigned int status = desc->status & ~IRQ_DISABLED;
 123
 124                 /* Prevent probing on this irq: */
 125                 desc->status = status | IRQ_NOPROBE;
 126                 check_irq_resend(desc, irq);
 127                 /* fall-through */
 128         }
 129         default:
 130                 desc->depth--;
 131         }
 132         spin_unlock_irqrestore(&desc->lock, flags);
 133 }
 134 EXPORT_SYMBOL(enable_irq);
 135
 136 /**
 137  *      set_irq_wake - control irq power management wakeup
 138  *      @irq:   interrupt to control
 139  *      @on:    enable/disable power management wakeup
 140  *
 141  *      Enable/disable power management wakeup mode
 142  */
 143 int set_irq_wake(unsigned int irq, unsigned int on)
 144 {
 145         struct irq_desc *desc = irq_desc + irq;
 146         unsigned long flags;
 147         int ret = -ENXIO;
 148
 149         spin_lock_irqsave(&desc->lock, flags);
 150         if (desc->chip->set_wake)
 151                 ret = desc->chip->set_wake(irq, on);
 152         spin_unlock_irqrestore(&desc->lock, flags);
 153         return ret;
 154 }
 155 EXPORT_SYMBOL(set_irq_wake);
 156
 157 /*
 158  * Internal function that tells the architecture code whether a
 159  * particular irq has been exclusively allocated or is available
 160  * for driver use.
 161  */
 162 int can_request_irq(unsigned int irq, unsigned long irqflags)
 163 {
 164         struct irqaction *action;
 165
 166         if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
 167                 return 0;
 168
 169         action = irq_desc[irq].action;
 170         if (action)
 171                 if (irqflags & action->flags & SA_SHIRQ)
 172                         action = NULL;
 173
 174         return !action;
 175 }
 176
 177 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 178 {
 179         /*
 180          * If the architecture still has not overriden
 181          * the flow handler then zap the default. This
 182          * should catch incorrect flow-type setting.
 183          */
 184         if (desc->handle_irq == &handle_bad_irq)
 185                 desc->handle_irq = NULL;
 186 }
 187
 188 /*
 189  * Internal function to register an irqaction - typically used to
 190  * allocate special interrupts that are part of the architecture.
 191  */
 192 int setup_irq(unsigned int irq, struct irqaction *new)
 193 {
 194         struct irq_desc *desc = irq_desc + irq;
 195         struct irqaction *old, **p;
 196         unsigned long flags;
 197         int shared = 0;
 198
 199         if (irq >= NR_IRQS)
 200                 return -EINVAL;
 201
 202         if (desc->chip == &no_irq_chip)
 203                 return -ENOSYS;
 204         /*
 205          * Some drivers like serial.c use request_irq() heavily,
 206          * so we have to be careful not to interfere with a
 207          * running system.
 208          */
 209         if (new->flags & SA_SAMPLE_RANDOM) {
 210                 /*
 211                  * This function might sleep, we want to call it first,
 212                  * outside of the atomic block.
 213                  * Yes, this might clear the entropy pool if the wrong
 214                  * driver is attempted to be loaded, without actually
 215                  * installing a new handler, but is this really a problem,
 216                  * only the sysadmin is able to do this.
 217                  */
 218                 rand_initialize_irq(irq);
 219         }
 220
 221         /*
 222          * The following block of code has to be executed atomically
 223          */
 224         spin_lock_irqsave(&desc->lock, flags);
 225         p = &desc->action;
 226         old = *p;
 227         if (old) {
 228                 /*
 229                  * Can't share interrupts unless both agree to and are
 230                  * the same type (level, edge, polarity). So both flag
 231                  * fields must have SA_SHIRQ set and the bits which
 232                  * set the trigger type must match.
 233                  */
 234                 if (!((old->flags & new->flags) & SA_SHIRQ) ||
 235                     ((old->flags ^ new->flags) & SA_TRIGGER_MASK))
 236                         goto mismatch;
 237
 238 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
 239                 /* All handlers must agree on per-cpuness */
 240                 if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU))
 241                         goto mismatch;
 242 #endif
 243
 244                 /* add new interrupt at end of irq queue */
 245                 do {
 246                         p = &old->next;
 247                         old = *p;
 248                 } while (old);
 249                 shared = 1;
 250         }
 251
 252         *p = new;
 253 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
 254         if (new->flags & SA_PERCPU_IRQ)
 255                 desc->status |= IRQ_PER_CPU;
 256 #endif
 257         if (!shared) {
 258                 irq_chip_set_defaults(desc->chip);
 259
 260                 /* Setup the type (level, edge polarity) if configured: */
 261                 if (new->flags & SA_TRIGGER_MASK) {
 262                         if (desc->chip && desc->chip->set_type)
 263                                 desc->chip->set_type(irq,
 264                                                 new->flags & SA_TRIGGER_MASK);
 265                         else
 266                                 /*
 267                                  * SA_TRIGGER_* but the PIC does not support
 268                                  * multiple flow-types?
 269                                  */
 270                                 printk(KERN_WARNING "setup_irq(%d) SA_TRIGGER"
 271                                        "set. No set_type function available\n",
 272                                        irq);
 273                 } else
 274                         compat_irq_chip_set_default_handler(desc);
 275
 276                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 277                                   IRQ_INPROGRESS);
 278
 279                 if (!(desc->status & IRQ_NOAUTOEN)) {
 280                         desc->depth = 0;
 281                         desc->status &= ~IRQ_DISABLED;
 282                         if (desc->chip->startup)
 283                                 desc->chip->startup(irq);
 284                         else
 285                                 desc->chip->enable(irq);
 286                 } else
 287                         /* Undo nested disables: */
 288                         desc->depth = 1;
 289         }
 290         spin_unlock_irqrestore(&desc->lock, flags);
 291
 292         new->irq = irq;
 293         register_irq_proc(irq);
 294         new->dir = NULL;
 295         register_handler_proc(irq, new);
 296
 297         return 0;
 298
 299 mismatch:
 300         spin_unlock_irqrestore(&desc->lock, flags);
 301         if (!(new->flags & SA_PROBEIRQ)) {
 302                 printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__);
 303                 dump_stack();
 304         }
 305         return -EBUSY;
 306 }
 307
 308 /**
 309  *      free_irq - free an interrupt
 310  *      @irq: Interrupt line to free
 311  *      @dev_id: Device identity to free
 312  *
 313  *      Remove an interrupt handler. The handler is removed and if the
 314  *      interrupt line is no longer in use by any driver it is disabled.
 315  *      On a shared IRQ the caller must ensure the interrupt is disabled
 316  *      on the card it drives before calling this function. The function
 317  *      does not return until any executing interrupts for this IRQ
 318  *      have completed.
 319  *
 320  *      This function must not be called from interrupt context.
 321  */
 322 void free_irq(unsigned int irq, void *dev_id)
 323 {
 324         struct irq_desc *desc;
 325         struct irqaction **p;
 326         unsigned long flags;
 327
 328         WARN_ON(in_interrupt());
 329         if (irq >= NR_IRQS)
 330                 return;
 331
 332         desc = irq_desc + irq;
 333         spin_lock_irqsave(&desc->lock, flags);
 334         p = &desc->action;
 335         for (;;) {
 336                 struct irqaction *action = *p;
 337
 338                 if (action) {
 339                         struct irqaction **pp = p;
 340
 341                         p = &action->next;
 342                         if (action->dev_id != dev_id)
 343                                 continue;
 344
 345                         /* Found it - now remove it from the list of entries */
 346                         *pp = action->next;
 347
 348                         /* Currently used only by UML, might disappear one day.*/
 349 #ifdef CONFIG_IRQ_RELEASE_METHOD
 350                         if (desc->chip->release)
 351                                 desc->chip->release(irq, dev_id);
 352 #endif
 353
 354                         if (!desc->action) {
 355                                 desc->status |= IRQ_DISABLED;
 356                                 if (desc->chip->shutdown)
 357                                         desc->chip->shutdown(irq);
 358                                 else
 359                                         desc->chip->disable(irq);
 360                         }
 361                         spin_unlock_irqrestore(&desc->lock, flags);
 362                         unregister_handler_proc(irq, action);
 363
 364                         /* Make sure it's not being used on another CPU */
 365                         synchronize_irq(irq);
 366                         kfree(action);
 367                         return;
 368                 }
 369                 printk(KERN_ERR "Trying to free free IRQ%d\n", irq);
 370                 spin_unlock_irqrestore(&desc->lock, flags);
 371                 return;
 372         }
 373 }
 374 EXPORT_SYMBOL(free_irq);
 375
 376 /**
 377  *      request_irq - allocate an interrupt line
 378  *      @irq: Interrupt line to allocate
 379  *      @handler: Function to be called when the IRQ occurs
 380  *      @irqflags: Interrupt type flags
 381  *      @devname: An ascii name for the claiming device
 382  *      @dev_id: A cookie passed back to the handler function
 383  *
 384  *      This call allocates interrupt resources and enables the
 385  *      interrupt line and IRQ handling. From the point this
 386  *      call is made your handler function may be invoked. Since
 387  *      your handler function must clear any interrupt the board
 388  *      raises, you must take care both to initialise your hardware
 389  *      and to set up the interrupt handler in the right order.
 390  *
 391  *      Dev_id must be globally unique. Normally the address of the
 392  *      device data structure is used as the cookie. Since the handler
 393  *      receives this value it makes sense to use it.
 394  *
 395  *      If your interrupt is shared you must pass a non NULL dev_id
 396  *      as this is required when freeing the interrupt.
 397  *
 398  *      Flags:
 399  *
 400  *      SA_SHIRQ                Interrupt is shared
 401  *      SA_INTERRUPT            Disable local interrupts while processing
 402  *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 403  *
 404  */
 405 int request_irq(unsigned int irq,
 406                 irqreturn_t (*handler)(int, void *, struct pt_regs *),
 407                 unsigned long irqflags, const char *devname, void *dev_id)
 408 {
 409         struct irqaction *action;
 410         int retval;
 411
 412         /*
 413          * Sanity-check: shared interrupts must pass in a real dev-ID,
 414          * otherwise we'll have trouble later trying to figure out
 415          * which interrupt is which (messes up the interrupt freeing
 416          * logic etc).
 417          */
 418         if ((irqflags & SA_SHIRQ) && !dev_id)
 419                 return -EINVAL;
 420         if (irq >= NR_IRQS)
 421                 return -EINVAL;
 422         if (irq_desc[irq].status & IRQ_NOREQUEST)
 423                 return -EINVAL;
 424         if (!handler)
 425                 return -EINVAL;
 426
 427         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 428         if (!action)
 429                 return -ENOMEM;
 430
 431         action->handler = handler;
 432         action->flags = irqflags;
 433         cpus_clear(action->mask);
 434         action->name = devname;
 435         action->next = NULL;
 436         action->dev_id = dev_id;
 437
 438         select_smp_affinity(irq);
 439
 440         retval = setup_irq(irq, action);
 441         if (retval)
 442                 kfree(action);
 443
 444         return retval;
 445 }
 446 EXPORT_SYMBOL(request_irq);
 447